Rotating an Alluvial Plot to flow downwards or upwards

[ericmelse]

Dear Asjad,

For lack of time right now, I cannot provide a hand made example and further explain its purpose (but I will add that later), but could you make it possible to rotate an Alluvial Plot so that the 'flows' in between the categorical nodes run upwards or downwards (depending on we should 'read' them)?
Typically that would only be a rotation of 90 degrees clockwise or counter-clockwise.
Ofcourse I can do that in a graphic editor but I want to be able to control the display using code.

[asjadnaqvi]

Changing the orientation is on the todo list for several packages.